Annan began his quest last winter after hearing Richard Lindzen, a meteorologist at the Massachusetts Institute of Technology who questions the extent to which human activities are influencing climate, say he was willing to bet that global temperatures will drop over the next 20 years. ...

But no wager was ever agreed. Annan says that Lindzen wanted odds of 50-to-1 against falling temperatures: this meant that Annan would pay out $10,000 if temperatures dropped, but receive only $200 if they rose. In total, Annan says he tried and failed to agree terms with seven sceptics.

... In May, environmental activist George Monbiot challenged climate sceptic Myron Ebell to a £5,000 (US$9,000) wager live on BBC radio. Ebell, a global-warming specialist at the Competitive Enterprise Institute, a think-tank in Washington DC, declined, saying he has four children to put through university and so does not “want to take risks”.

Annan’s search ended with Mashnich and Bashkirtsev, who are based at the Institute of Solar-Terrestrial Physics in Irkutsk, Russia. They say that global surface air temperatures closely correlate with the size and number of sunspots. Sunspot levels follow regular patterns and the Sun is expected to be in a less active phase over the next few decades, leading Mashnich and Bashkirtsev to predict a drop in temperature.

The results were in a while ago, and of course Annan won easily, as the blue lines in the graph below show. ...

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